The present invention relates to blow molding of articles from thermoplastic material, and particularly, to a method of and an apparatus for molding a container which has an angular neck.
It is known to produce containers by blow molding techniques wherein the containers have off-set or angularly disposed necks or spouts. These techniques include multiple stage operations, wherein the parison is extruded and clamped in the mold at one station and a blow pin is inserted into the mold for blowing and/or compression molding of the neck at another station. Techniques of this character increase the cost of the container because of the tooling costs involved and also because they limit the extent of use that can be made of standard extrusion and blow molding apparatus of the type that has a conventional extrusion head with a downwardly opening annular orifice and a coaxially positioned blow pin.
Normally, this standard type of apparatus cannot be used in a satisfactory manner to mold at one station the container with an angular neck, because to do so would require the mold cavity to be aligned so that the angular neck is axially aligned with the blow pin and the annular extrusion orifice. This creates significant problems, especially with respect to irregular wall thicknesses in the blown container.